The overall objective of this research is to determine the genetic linkage relationships of a spinocerebellar ataxia gene inherited in autosomal dominant pattern in a large kindred in which preliminary data indicates close linkage to the HL-A histocompatibility complex. In addition to HL-A, Glyoxalase I, Pepsinogen-5, blood group P, and phosphoglucomutase-3, all possibly within measurable linkage distance on human chromosome 6, will be studied. Information of value should be yielded both for mapping chromosome 6 in man and for establishing linkage relationships of a disorder roughly equivalent in social impact to Huntington's Chorea. Thus more precise genetic counseling can be provided in this and possibly other families.